JPH0468876A - Video photographing device for measuring high flow velocity place - Google Patents

Abstract

PURPOSE:To enable consecutive photographing with short time difference by using a prism or a mirror to divide incident light and executing photographing while shifting time among plural imaging devices. CONSTITUTION:This video photographing device is a three-panel system using three imaging devices, a beam split prism 11 is arranged to split the beam made incident from an image pickup lens system 10. The incident light is almost equally splitted into three beams by a 1/3 reflecting film 12 and a 1/2 reflecting film 13 so that the same image can be formed respectively on the photodetecting faces of CCD imaging devices 14, 15 and 16 counter arranged counter to three emitting faces 11a, 11b and 11c. When executing consecutive photographing to three monochromatic pictures with short time difference, a synchronizing signal is outputted to instruct photographing time while shifting time difference from a synchronizing signal generator 40 to the three imaging devices 14-16 and preamplifiers 31A-31C corresponding to the respective imaging devices. Picture signals from the respective imaging devices 14-16 are serially recorded to a solid-state memory 33, read out by a computer 34 for picture constitution and reproduced to three pictures.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a video recording device for measuring high-speed flow fields, and is useful for measuring fluid motion such as high-speed turbulence, high-speed moving objects, destructive phenomena, electric discharge phenomena, chemical reaction phenomena, etc. It is also suitable for use in elucidating the following.

Conventional technology and the problem to be solved by the invention In the past, technology development regarding point measurement of flow velocity has progressed, but technology for measuring flow velocity field in area, especially high-speed turbulent flow velocity field continuously for a long period of time, has been developed. No video recording equipment is provided that can measure resolution.

In the fluid motion described above, the mutual positional relationship between the fluid parts changes, and in this respect it is completely different from the case of object motion. For example, in the human body, the hands are placed under the neck and on the sides of the torso, but in fluid motion, the hands can be switched left, right, up, or down in any case depending on the movement conditions. Therefore, for example, when measuring a flow velocity field by photographing and tracking a large number of solid particles mixed in a fluid with a video camera, nothing can be learned by looking at the positional relationship between the particles in one image. It becomes meaningful only when the positional deviation of each particle is measured from two or more consecutive images taken with a short time difference, and the sequence at each point or the entire flow velocity field can be determined. In fact, most of the basic equations of fluid motion, such as the Nahir-Stokes equation, use flow velocity as a variable, not position.

Therefore, when shooting with a video device, if the frame rate per image sensor is, for example, 1.000 frames per second, two to three consecutive images with a short time difference can be obtained every I/10.000 seconds. , the flow velocity field can be determined every 1/1,000 seconds, which is extremely convenient for fluid analysis.

Also, with only two consecutive images, for example, it may be difficult to associate particles in the first image with particles in the second image, so the third or fourth image is used as an auxiliary image. There is a need to improve the reliability of measurements by

When measuring fluid motion in this way, the frame rate of one image sensor is about 1/10 to 1. It is necessary to obtain at least two consecutive images within one frame rate of one image sensor with a short time difference of about /1.00.

On the other hand, for professional color photography at broadcasting stations, etc., a three-frame video camera is often used. As shown in FIG. 9, the three-frame video system includes a dichroic prism 2 arranged behind an imaging lens 1, and a dichroic surface 3 provided with a layer that transmits or reflects only a predetermined color within the prism.
In addition to providing A and 3B, the above prescribed colors (green, red, blue)
Image sensors (including image pickup tubes) 4A, 4B, 4C that receive light
A color image is obtained by synchronizing photographing with these three image sensors.

The present invention is a method that allows continuous shooting with a short time difference.
Focusing on the above-mentioned three-frame video camera using three image sensors, the basic configuration of the video camera using multiple image sensors was utilized and improved. By using a prism or mirror that simply splits the incident light instead of a dichroic prism, and by using multiple image sensors to take images at different times, it is possible to take continuous images with extremely short time differences.
Our company provides a video recording device suitable for use in measuring high-speed flow fields.

As mentioned above, the time difference between multiple image sensors is, for example, when the frame rate of each image sensor is 1,000 frames per second, the time difference between the shooting times of three image sensors is usually 1/10,000 second, The maximum time difference is 1/100 millionth of a second, and it is particularly important to be able to obtain three consecutive images with a time difference of 10,000 to 1/100 millionth of a second every I/1,000 second. This is preferable for flow velocity field measurements.

In addition, when the time difference between the plurality of image sensors is 1/T seconds, which is the frame rate of one image sensor, images are taken with a time difference of 1/(T - M) seconds or a smaller time difference. It is also preferable to set it to .

Furthermore, a color optical filter can be removably mounted in front of the light-receiving surface of the image sensor, and the shooting time of each image sensor can be completely matched, making it possible to use it for color photography. be.

Means for solving the problem, that is, the present invention provides a prism or a mirror that splits incident light behind an imaging lens, and at least two or more M imaging elements that receive the split light. The same image is formed on these image sensors to receive light, and an optical filter loading section for removably loading an optical filter is provided in front of the light receiving surface of each image sensor. A synchronizing signal generator is provided which periodically outputs a signal instructing the imaging time to the image sensor, the signal processing unit and the memory unit of the image sensor, and the synchronizing signal generator is configured to transmit the synchronizing signal to the M image sensors. The time difference and gate oven time are arbitrarily set and output so that one set of M consecutive images can be obtained consecutively at an arbitrarily short interval within the same time interval as the frame rate of one image sensor. The present invention provides a video photographing device for measuring high-speed flow velocity fields.

In the above-mentioned video shooting device, the incident light is divided into three by a prism and the image sensor is arranged in the same manner as the conventional three-plate structure, and the incident light is divided into two and the image sensor is arranged in the same way as the conventional two-plate structure. Any method of arranging the image sensor can be arbitrarily adopted.

Furthermore, in the case of high-speed continuous shooting in which images are taken with a short time difference using two or more M image sensors as described above, there is often a lack of light, so in addition to compensating for this lack of light, the second step is to perform pre-1L. An image innotenon fire that can be captured at high speed and increases the amount of light is attached to the lens system disposed in front of the light splitting prism or mirror, and the Preferably, the configuration is such that the synchronization signal generator outputs the synchronization signal.

Furthermore, when used for color photography, in order to compensate for insufficient light quantity and to prevent pre-loading, high speed It is also possible to install an image inotenon fire that can be used for color photography, and to output a synchronization signal from the synchronization signal generator to M image sensors simultaneously and periodically to indicate the shooting time. It is preferable to make it suitable for use.

When using a microchannel plate type image inotenon fire (hereinafter referred to as MCP) as an image inotenon fire capable of high-speed gating as described in Section 2, it has a light amplification function, an ultra-high-speed gating function, a light receiving pattern retention function (fluorescence (due to the afterimage of the surface) are all satisfied.

In addition, the optical filter loading section above has colors (green, red, blue).
It goes without saying that instead of loading an optical filter, various optical filters used for scientific measurements can be loaded.

Effect: When using the above-mentioned video recording device according to the present invention, several sets of consecutive images are taken with a very short time difference, and these sets are obtained continuously at a high frame rate. can be recorded in the form of electrical signals.

For example, in the case of a three-plate system with three image sensors arranged, the frame rate of one image sensor is set to 1.000 frames per second, and the shooting time difference of the three image sensors is set to 1/10.0.
If the images are shifted by 00 seconds, three consecutive images can be obtained within one frame rate with a time difference of 1/10,000 seconds, which is particularly preferable for measuring flow velocity fields. In addition, when the frame rate of one image sensor is 1,000 frames/second, the shooting time difference of three image sensors should be 1/3,000 seconds, in this case, 1/3,00
It is not possible to obtain a flow velocity field every 0 seconds, or it is possible to take pictures using a normal video device.

In addition, Image Inotenon Fire's ultra-fast gaiting nog function (up to 1 second for several coats) and light enhancement function (10,0
00 times or more) and the afterglow characteristics of the fluorescent screen (1/10,00
0 to 1/1,000 second) as a buffer memory, three consecutive images can be obtained with a time difference of up to 1/100 millionth of a second, and a set of three consecutive images like this can be obtained. or every 1/1.000 seconds.

As mentioned above, the significance of stopping research and development in being able to obtain two or three consecutive images with a short time difference after a certain period of time is as follows.
This is particularly important in fluid engineering.

Furthermore, if three-color optical filters (red, green, and blue) are attached to the front of the three image sensors, and the time difference between the three images is set to zero, it is possible to take high-speed color images at a rate of 1,000 images per second. can.

Hereinafter, the present invention will be explained in detail with reference to embodiments shown in the drawings.

1 to 3 show a first embodiment of the present invention, which is a three-image type using three image sensors.

A beam splitting prism l'l for splitting the light incident from the imaging lens system IO is arranged behind the imaging lens system IO, and a 1/3 reflective film 12 and a 1/2 reflective film provided in the beam splitting prism 11 are arranged. The incident light is divided almost equally into three by the reflective film 13, and these divided incident lights are sent to the three exit surfaces 11a, 1 of the beam split prism l■.
CCD image pickup device I4.lb and 11c are arranged opposite to each other.
The same image is formed on the light receiving surfaces of 15 and 16, respectively.

Incidentally, the above-mentioned image sensor is not limited to COD, but MO5
A type image sensor may be used, or an image pickup tube may also be used.

Optical filter loading sections 20a to 20c (no. (shown in Figure 2). These optical filter loading parts 2Ga to 20c consist of gaps 21a to 21c formed between each image sensor [4 to I6 and each beam split prism exit surface 11a=11c, and one end of these gaps 21a to 21c is connected to the camera body 22. Recessed stopper portions 23a to 23c are formed to position and hold the optical filters when they are loaded into the gaps 21a to 21c. Moreover, each of the gaps 21a to 21c has an opening on the outer surface which is normally closed with a cover (not shown) or the like, so that the optical filters 17 to 19 can be inserted and taken out through the opening. The above imaging lens system I
An image intenon fire loading section 26 in which an image intenon fire 25 can be removably loaded is also provided between the image intenon fire loading section 26, and the image intenon fire 25 is fixedly arranged within the image intenon fire loading section 26.

The external signal processing mechanism 30, which is separate from the camera body, is provided with preamplifiers 31A to 31C connected to the image sensors 14 to 16 built into the camera body, respectively, and these preamplifiers 31A to 31C are connected to the A/D converter 32. And,
The A/D converter 32 is connected to a solid-state memory 33, and the signals output from each of the image sensors 14 to I6 are once recorded in the solid-state memory 33 serially as they are in a so-called trickle-down method. The solid-state memory 33 includes an image composition computer 34;
An image processing device 35 is connected, and a reproduction monitor 36 is connected to the image processing device 35.

The image composition computer 34 converts the signal recorded in the solid-state memory 33 into three monochrome images per frame if no optical filter is installed, or after converting the signal recorded in the solid-state memory 33 into three monochrome images per frame, or if an optical filter is installed. One color image is constructed from three monochrome images per frame and is recorded in the solid state memory 33 in the form of a frame memory or the like. An image processing device 35 connected to the solid-state memory 33 performs measurement processing such as converting the three monochrome images into a flow velocity field in the l frame.

Further, when each of the image pickup devices 14 to 16 and the image intenon fire 25 are loaded, a synchronization signal generation device 40 is provided which is connected to the image intenon fire 25 and each of the preamplifiers 31A to 31C. A synchronization signal for instructing the shooting time is periodically sent. When a monochrome image is to be photographed at high speed without loading the optical filters 17 to 19, the synchronization signal instructing the photographing time is set with a time difference in the synchronization signal to each image sensor, and the synchronization signal instructs the photographing time and the gate oven time. It is set to send an instruction signal.

On the other hand, when color photographing is performed with the optical filters 17 to 19 loaded, a setting is made such that an instruction signal is sent to each image sensor to simultaneously perform photographing.

Next, the operation of the above photographing device will be explained.

First, we shot three monochrome images in succession with a short time difference.
When measuring the flow velocity field at high speed and in a planar manner, the optical filters 17-
Remove 19. The synchronizing signal generator 40 outputs a synchronizing signal instructing the photographing time by shifting the time difference to the three image sensors 7-14 to 16 and the preamplifiers 31A to 31G corresponding to each image sensor. At that time, the image sensors 14 to 1
When the maximum frame rate of 6 is 5 frames per second, the frame rate remains the same, and the gating time difference and gate open time are arbitrarily adjusted to create three triggers that are perfectly synchronized every second, for example. Based on each synchronization signal, a signal for opening and closing the gate is sent through a delay circuit corresponding to the time difference set for each image sensor 14 to 16. Each image sensor 14~
The image signal from 16 is sent to the preamplifier 3 as described above.
1A to 31 C, solid state memory 3 via A/D converter 32
The recorded signals are read out by an image composition computer 34 and converted into three monochrome images.

That is, as shown in FIG. 3, when the frame rate of one image sensor is t, o o o frames/second, the shooting start times t1, t7, t3 of the three image sensors 14 to 16 are /1
Shift each image sensor 14 to 16 by 0,000 seconds.
Shooting time of 1. /10.000 seconds, then l/10
With a time difference of ,000 seconds, three consecutive images are obtained every 1/1,000 seconds. Like this I/10,000
If three consecutive images with a short time difference are obtained every second, I/1
．． The flow velocity field can be determined every 000 seconds, making fluid analysis easier.

However, with only three consecutive images, the particles in the first image and the particles in the second
In some cases, it may be difficult to correlate the particles with the particles in the second image, and in that case, as shown in FIG.
The gate of the image sensor 16 is opened (imaging time T 3 = T, ±T2 of the image sensor 16, imaging start time t3 is made to match tl). By setting the shooting start time and shooting time in this way, as shown in Fig. 5, you can shoot the so-called flow line and know the flow pattern, and at the same time,
The flow velocity can be measured with high accuracy from the position of the particle itself in the second image.

Is the above shooting for tracking the movement of a large number of particles?
Another way to determine the flow velocity field is to measure it from the concentration field of a dye or the like mixed in with the fluid. In this case as well, as mentioned above, two or three consecutive images taken at short time differences are required, resulting in one flow velocity field every 1/1,000 seconds.

In addition, the frame rate of one image sensor is 1,000 images/
seconds, the shooting start time of the three image sensors is 1/3,
000 seconds at a time, and each image is captured.

If the imaging time of the element is 1/3,000 seconds, in this case, although it is not possible to obtain a flow velocity field every 1/3,000 seconds, normal high-speed imaging can be performed.

Particularly in cases where the amount of light is insufficient for ultra-high-speed photography under weak conditions, it is preferable to load the image intensifier 25 into the image intensifier loading section 26 provided in the lens system IO.

As the image intensifier 25, a microchannel plate (MCP) type is used, and the MCP has a light intensification function of more than IO,000 times. You can solve fewer problems. Furthermore, because it has an ultra-high-speed gating mechanism (maximum 1 second for several coatings), it is possible to obtain three consecutive images with a time difference of about 1/100 millionth of a second. Furthermore, if the afterglow characteristic of the phosphor screen (approximately 1/10,000 to 1/1000 seconds) is utilized as a buffer memory, three consecutive images can be obtained with a time difference of up to 1/100 millionth of a second. Therefore, it is possible to measure ultra-high-speed fluid interaction such as jet ennon injection and plasma.

Note that when an MCP type image intensifier 25 is interposed in the lens system, the light coupling loss is large, so it is necessary to further add an image conoverter type image intensifier after the MCP to compensate for the lack of light amount. Occurs in some cases. In addition, the gating period of MCP is up to 1
/I O,000 seconds, so the time from -degree gating to the next gating cannot be shortened to less than that,
Therefore, the time difference between the three images cannot be made smaller than that.

On the other hand, when photographing in color using the above-mentioned photographing device, the sixth
As shown in the figure, green, red, and blue optical filters 17 to 19 are loaded into the optical filter loading sections 20a to 20c, and three image pickup devices 14 to 16 are loaded from the synchronization signal generator 40.
A synchronization signal is sent to the camera with the shooting start time and gating time completely aligned. The image output signals from the image sensors 14 to 16 are converted into digital signals through the preamplifiers 31A to 31C and the A/D converter 32, as in the case of monochrome photography, and then converted into digital signals in a serial manner as they are. It is temporarily recorded in the memory 33. When playing,
By simply changing the computer software for image reproduction, the image composition computer 34 composes one color image from three monochrome images, and records this in a solid-state memory in the form of a frame memory or the like.

FIG. 7 shows a second embodiment of the present invention, in which three image pickup devices 14 to 16 each have an MCP type image intensifier 25 built-in in advance. That is, the MCP is fixed to the front surface of the light receiving surface of each of the image sensors 14 to 16. In this way, when the MCP is attached to each of the image sensors 14 to 16, there is no need to compensate for the lack of light quantity, and therefore there is no need to attach an image converter type image intensifier. Therefore, there is almost no image distortion, and the time difference between each image sensor can be reduced to about 1/100 millionth of a degree at most.

In the case of color photography, the amount of light is 1772 to 1/4 compared to a dichroic prism for normal color photography, or an image intensifier with a light-enhancing effect is installed in front of each image sensor as described above. By installing this, you can solve the problem of insufficient light.

FIG. 8 shows a third embodiment of the present invention, which is of a two-image type in which incident light is divided into two and the divided incident light is received by two image pickup elements. In the photographing device, a semi-transparent film 5I is provided within the beam split prism 50 to split the incident light into two, and the exit surface 50a of the prism 50 is provided with a semi-transparent film 5I.
, 50b, two image pickup devices 52 and 53 are installed facing each other.

16. An optical filter loading section is installed in front of each image sensor 52 and 53, and a green optical filter 54 is installed for color photography.
and a red and blue array optical filter 55 are loaded, and a relay lens 56 is loaded between the optical filter 55 and the image pickup element 53.

The two-image photographing device described above differs from the three-image photographing device of the first embodiment in that only two or three images can be obtained consecutively within one frame with a short time difference, and the rest are the same. Therefore, the explanation will be omitted.

Effects of the Invention As is clear from the above explanation, according to the photographing device according to the present invention, by removing the optical filter and shifting the photographing time of a plurality of image pickup devices, the frame rate of one image pickup device can be reduced by 1%. /10 to 1/100, for example, 1
It is possible to take 2 to 3 monochrome images with an extremely short time difference of /10,000 seconds, making it suitable for tracking the movement (positional relationship) of particles in high-speed fluids and measuring flow velocity. It can be used. In addition to the above-mentioned fluid measurement, we also conduct research and development that is effective in the observation and image analysis of various phenomena that change rapidly across industries, such as explosion phenomena, turbulent flow phenomena, destructive phenomena, and within the field of view of a microscope. It can also be suitably used to elucidate biological and chemical phenomena that change rapidly.

In this R1 device, when you want to take color photographs, you load a color optical filter into the optical filter loading section, and the output signal from the image sensor is A/D converted and stored in high-speed memory as a digital signal. 7. Since it is recorded in real time using the so-called dripping method, and the computer software is changed during playback to reproduce the image, it can be used for color photography. In this way, one video camera can be used for ultra-high-speed continuous shooting of black and white images, and can also be used for color shooting, which has the advantage of being compatible with a variety of uses. .

[Brief explanation of the drawing]

FIG. 1 is an overall view of the first embodiment of the present invention, FIG. 2 is an enlarged cross-sectional view of the main part of the first embodiment, and FIGS. 3 and 4 are high-speed black and white photography using the imaging device according to the 11th embodiment. A diagram showing a photographing pattern, FIG. 5 is a schematic diagram showing an image configuration according to the photographing pattern of FIG. 4, and FIG. 6 is an enlarged view of main parts showing the state during color photographing with the photographing device of the first embodiment. FIGS. 7 and 8 are enlarged views of main parts showing second and third embodiments of the present invention, and FIG. 9 is a drawing showing main parts of a conventional three-plate color photographing device. 10-Lens system, 11. Heam split prism, 14-16...Image sensor, 17-19.Optical filter, 25.. Image intensifier, 31A-31C
- Preamplifier, 32... A/D converter, 33... Solid-state memory, 34... Image composition computer, 35-... Image processing device, 40... Synchronization signal generation device. Figure 2 Figure 3 Figure 1 Frame

Claims (1)

[Claims] 1. A prism or a mirror that splits incident light is arranged behind the imaging lens, and at least two or more M imaging devices that receive the split light are provided, and these imaging devices An optical filter loading section is provided to form the same image on the light-receiving surface and to removably load an optical filter on the front surface of the light-receiving surface of each image sensor. A synchronizing signal generating device is provided which periodically outputs a signal instructing the photographing time to the unit and the memory unit, and the synchronizing signal generating device sends the synchronizing signal to the M image sensors according to the time difference of the synchronizing signal and the gate open time as desired. , and output one of M consecutive images within the same time interval as the frame rate of one image sensor.
1. A video photographing device for measuring a high-speed flow velocity field, characterized in that sets are continuously obtained at arbitrarily short intervals. 2. The synchronization signal output from the synchronization signal generator to the M image sensors is such that the frame rate of one image sensor is 1/
2. The video photographing apparatus according to claim 1, wherein the video photographing apparatus is set to take photographs at a time difference of less than 1/(T·M) seconds when the time is T seconds. 3. An image intensifier capable of high-speed gating is attached to the lens system disposed in front of the light splitting prism or mirror, and the synchronization is performed so that the image intensifier is synchronized with the M image pickup devices. 2. The video photographing apparatus according to claim 1, wherein the signal generating device outputs a synchronizing signal. 4. An image intensifier capable of high-speed gating is installed between the front surface of the light receiving section of the M image pickup devices and the optical filter loading section, and an image intensifier capable of high-speed gating is installed between the front surface of the light receiving section of the M image pickup devices, and 2. The video photographing apparatus according to claim 1, wherein the video photographing apparatus is configured to output a synchronization signal to the M image pickup devices simultaneously and periodically to instruct a photographing time point.